Airplane empennage



Jan. 3, 1939. J. 5. MCDONNELL, JR 2,142,450

AIRPLANE EMPENNAGE Filed June 25, 1957 2- Sheets-Sheet 1 INVENTOR. JAMES 5.1"1 DONNELL JR.

- I BY ATTORNEY.

Jan. 3, 1939. J. S. M DONNELL, JR 2,142,450

AIRPLANE EMPENNAGE Filed June 25 1937 2 Sheets-Sheet 2 INVENTOR. JAMES S. M DONNELLJR.

ATTORNEY.

Patented Jan. 3, 1939 UNITED STATES PATENT OFFICE AIRPLANE EMPENNAGE Application June 25, 1937, Serial No. 150,241

4 Claims.

This inventionrelates in general to improvement in aircraft construction and more particularly is directed to improvement in an airplane empennage, the disclosure being directed to such an airplane empennage having a novel and improved means for increasing the stability of the aircraft and for greatly improving the operation of the control surfaces.

' flow being caused by the natural tendency of the air from the high pressure region below the elevator to flow to that of the low pressure region above it. The resultant upflow at the cutbacks at each end of the elevator, coupled with the induced transverse fiow feeding it, gives rise to a large proportion of the energy loss and wind resistance and causes a decreased impress of pitching moment of the aircraft.

,It is one object of the invention to provide a means for greatly improving the aerodynamic features of an airplane.

w Another object is the attainment of a greatly increased impress of pitching moment of the aircraft.

.A further object is the attainment of an increased impress of the energy and wind resistance of the aircraft. v

A still further object is the attainment of greatly improved and stabilized operation of the control surfaces.

The above and other objects will be'made ap- I parent throughout the further description of the invention when taken in connection with the accompanying drawings, wherein like reference characters refer to like parts. It is distinctly understood that the drawings are not a definition of the invention, but merely illustrate a preferred embodiment of the invention in connection with one particular type of installation.-

In the drawings:

Figure 1 is a perspective view of an airplane empennage having a single elevator in normal position, showing extended tip of the fuselage.

Figure 2 is a perspective view of the structure shown in Figure 1 with lowered single elevator.

Figure 3 is a top plan view of the structure of Figure 1, showing an improved method of attachinvention.

ing rudder to the fin in relation to a single elevator.

Figure 4 is a rear view of the structure shown in Figure 3.

Figure 5 is a front view of the structure shown 5 in Figure 3 with rudders and single elevator in neutral position.

Fig. 6 is a perspective view of an airplane empennage having dual elevators embodying the Fig. 7 is a similar view showing the elevators in lowered position.

Fig. 8 is a top plan view of the same end, and

, Fig. 9 is a front view of Fig. 8.

Referring now to the drawings, Figures lto 5, inclusive, indicate an airplane empennage '1 in its entirety having a single elevator l. Thesaid airplane empennage is situated centrally and transversely on the fuselage of which it is a part in such manner that tip 5 of said fuselage extends: rearwardsand under the trailing edge of stabilizer 3 to a point under the trailing edge of single elevator 4. The said single elevator extends laterally the entire span of stabilizer 3 and is hingedly mounted to its trailing edge.

Fins I and la are fastened respectively at each end of stabilizer 3, and perpendicularly to the span thereof in such manner that their trailing edge protrudes to the rear of the trailing edge of the said stabilizer and are adjacent to the ends of the single elevator 4, the purpose of which will be understood as the description of the invention progresses.

. Rudders 2 and 2a are hingedly connected by conventional means to fins land la respectively at each end of the stabilizer and it is therefore only necessary todescribe the-exact point at which this is done. The'trailing edge of fin l protrudes past the trailing edge of stabilizer 3 to the point of attachment 8 of rudder 2 to fin l 40 which trailing edge is sufilciently extended to enable rudder 2 to swing right without interference with single elevator l as shown in Figure3.

At the same time the ends of elevator 4, shown in the neutral position, are substantially horizontal and adjacent to each fin and do not interfere with the movement of the rudder 2, in this manner preventing the passage of an airflow from the high pressure area below the elevator l span of said stabilizer in such manner that their in this manner giving increased air resistance and energy to the aircraft.

Figures 6 to- 9, inclusive, indicate another form of the invention in which an airplane empennage i, possessing dual elevators 4a. and 4b, is shown, the said elevators being hingedly connected to stabilizer I and separated in such a manner that they form a triangular opening at their adjoining edges. Fins 2 and 2a are fastened respectively at each end of stabilizer 3 perpendicularly to the lage is on alevel with the surface of the dual elevators la and 4b in such manner that said triangular shaped surface of the extended tail fills a recess formed by the adjoining edges of dual elevators la and lb. At the same time dual elevators 4a and 4b are substantially horizontal, the outer edges of said dual elevators, while adjacent to fins I and la, respectively, do not interfere with the movement of rudder 2. In other words, fin .i forms a recess with extended tail 5 of the fuselage, thus permitting each elevator section to move freely in its particular recess.

The combination of extended tail 5 in correlation with the position of elevator ends in and 4b and fins I and la together with the extended position offins l and la greatly improves and stabilizes the operation of the control surfaces by increasing the impress of the energy and windresistance and serves as well to increase to a considerable degree the pitching moment of the aircraft.

I claim:

1. In combination, an airplane empennage comprising a stabilizer, a control 'surfacehingedly connected to the trailing edge of said stabilizer having at least one end extending parallel to the direction of flight, and means closely adjacent to each end of said control surface having vertical surfaces of sufiiciently greater vertical dimensions than the adjacent vertical faces of the control surface to cover the said vertical faces of the control surface in substantially all positions thereof for preventing spilling of air around i the ends of the control surface, at least the the end of the said control surface adjacent the fin 2. In combination, an airplane empennage comprising a stabilizer, a control surface hingedly connected to the trailing edge of said stabilizer having at least one end extending parallel to the direction of flight, and means closely adjacent to each end of said control surface having vertical surfaces of sufiiciently greater vertical dimensions than the adjacent vertical faces of the control surface to cover the said vertical faces of the control surface in substantially all positions thereof for preventing spilling of air around the ends of the control surface, at least the means at saidfirst mentioned end. comprising a fin 4 mounted on said stabilizer closely adjacent said first mentioned end and substantially perpendicular to the span thereof, and a rudder hinged to said fin at a point substantially in transverse alignment with the rearmost point of the portion of the said control surface adjacent the fin.

3. In combination, an airplane empennage comprising a stabilizer, a control surface hingedly connected to the trailing edge of said stabilizer having its ends extending parallel to the direction of fiight, and means at each end of said control surface for preventing spilling of air around the ends of the control surface, said means comprising fins mounted on said stabilizer closely adjacent said ends and substantially perpendicular to the span thereof, and rudders hinged to said fins at points at least'substantially as far to the rear as the rearmost points of the ends of the said control surface adjacent the fins.

4. In combination, an airplane empennage comprising a stabilizer, a control surface hingedly connected to the trailing edge of said stabilizer having its ends extending parallel to the direction of flight, and means at each end of said control surface for preventing spilling of air around the .ends of the control surface, said means comprising fins mounted on said stabilizer closely adjacent said ends and substantially perpendicular to the span thereof, and rudders hinged to said fins at points substantially in transverse alignment with the rearmost point of the ends of the said control surface adjacent the fins.

JAMES S. McDOIlNELL, JR. 

